Ok, so my next question would be:
We know it is a arm compiler, why we need a toradex SDK to compile?
For QT there is no board specific configuration needed like I2C or processor outputs. OpenGL can be disabled or loaded dynamically. I cannot find out how I compile it for general ArmV4I which is running on any ArmV4I board?
I did former use the QT4 embedded package. With this QT4 I do simple copy the dll files to any CE Arm4I platform. Now with QT5 it is not possible.

Since you wrote "# This is the Toradex SDK", I guess you are using e.g. their Colibri board. So they provide what is needed to develop properly on their device, whether you will use some or none of the hardware available is another question.

No, QT4 embeddd comes with pre- compiled dll files that work on CE of different boards. The linked QT page say it is not possible to be hardware independent with QT5 for a unknown reason.
However, the toradex SDK does not compile QT5 as described in first post, so I am lost.